"WAR beyond WAR" ???

"Evidence to the contrary?" Courier
"-You sound like the OTHER visitors. Making WILD claims of a WORLD beyond, where there is a WAR beyond WAR. It is UNPROVEN! And UNTHINKABLE!-" Borous

What is a war beyond war? He has to be talking about the NCR-Legion war. It can't be mere hyperbole because then it would more aptly apply the Great War. This doesn't really work as one of those senior moments contextually. Does he just mean the war that came after the Great war or something? That would be such a weird way to phrase it, if that's all he meant.

Regarding your first question, yes it pretty clear that Borous is speaking about the NCR - Legion war.
The first war he is talking about is the US-Sino war, of which the Great War is an extension off. (the Chinese launched their nukes when it was obvious that they could not defeat the US in a conventional way any more)

As for how it is phrased, understand that I am not an English speaker but it was pretty clear for me what he was talking about so I am not sure if it is really bad grammar.
I would also partly tie it into the guy's personality as he tends to speak in this tone/style about many subject.